This invention relates to a device for rotating valves, particularly the valves of internal combustion engines. The device has a control lever which is supported on the stationary engine housing and which is operatively connected with an overrunning clutch which, in turn, is coupled to the valve stem. The rotary motion imparted by the control lever to the overrunning clutch is transmitted by the latter to the valve stem only during the closing strokes of the valve.
A device of the above-outlined type is disclosed, for example, in German Pat. No. 1,301,333. In the device described in that patent, the drive of the overrunning clutch coupled with the valve stem is effected by a guide member which moves in a stationary slide track arranged at an oblique inclination to the direction of the valve stroke. The valve, as it executes its strokes, is rotated about the stem axis through an angle which is a function of the above-noted oblique inclination. By means of the overrunning clutch, the rotary motion is transmitted to the valve stem solely during the closing strokes of the valve in order to ensure a grinding action between the valve head and the valve seat as the valve closes.
It is a disadvantage of the above-outlined known valve rotating device that, particularly because of the slide-type guidance, it is expensive to manufacture. Further, its installation in the cylinder head causes construction problems, particularly in case of large engines, such as ship engines which have usually four valves for every cylinder. Further, a subsequent installation of the known rotating device on already existing engines (for example because of a conversion to another fuel such as heavy oil) is practically impossible.
Further, in case of a slide track of linear course, the angle of rotation of the valve is proportional to the stroke; thus, the rotational velocity is constant. In order to ensure, that, advantageously, the valve has a high rotary velocity shortly prior to its engagement with the valve seat, the slide track would have to be of arcuate course. This, however, would further increase the costs of manufacture, installation and particularly, adjustment. German Laid-Open Application (Offenlegungsschrift) No. 2,054,349 discloses a linkage drive which effects an accelerated rotation of the valve. The valve rotating device disclosed in the last-named reference, however, involves a relatively complex assembly and complex parts.
Further, in German Laid-Open Application (Offenlegungsschrift) No. 2,054,350 there is disclosed a valve rotating device, according to which the guide member sliding in a stationary slide track is directly connected with the sprags of the overrunning clutch. This valve rotating device, however, involves, because of its slide-type guide, the same problems inherent in the above-discussed German Pat. No. 1,301,333.